Verizon and other cell phone stores have the card readers in stock. I bought the Intuit one. It's a little larger than the Square, but works great just the same. They're all basically free after you insstall the software on your phone. I paid $20 and I was refunded the $20 after I set it up on my phone. A flat fee per transaction is nice, especially if you don't have a storefront and are only going to use it at shows, etc. I tested it a few times- swiping and entering the number manually. It works both ways just fine.
At Daytona I did see vendors that had heat tape run through their display racks. It was 90F outside, but the convention center was like 70F.
Pack a lunch. The food vendors (if there are any) are as expensive as Disney.
If you are staying in a hotel overnight make sure they will allow your animals also.
I was just thinking.... I'm sure there are "bugs" at the shows, but it just popped into my head- Does anyone QT their snakes when they get back from a show?? I'm thinking I would consider it.